The Diodes Inc PI4IOE5V9554ZHEX is a high-performance, 5 V tolerant, dual I²C-bus and SPI-bus compatible 16-bit I/O expander designed to extend general-purpose input/output capabilities in embedded and digital systems. It combines flexibility, low-power operation, and high integration, allowing system designers to increase I/O count without adding complex external circuitry.

The device operates over a wide voltage range and provides configurable input/output direction on each pin, programmable pull-up resistors, and interrupt capability to signal pin state changes. Its I²C-bus/SPI-bus interface enables simple integration with microcontrollers, FPGAs, and other digital controllers, making it suitable for applications in industrial control, consumer electronics, networking equipment, and battery-powered systems.

## Key Features

* 16-bit I/O expander with two 8-bit ports (Port 0 and Port 1)
* Dual-bus compatibility: I²C-bus (SMBus compatible) and SPI-bus interface
* 5 V tolerant inputs and outputs, supporting mixed-voltage systems
* Programmable input/output direction for each pin
* Configurable polarity inversion on input pins
* Integrated pull-up resistors, programmable per pin
* Interrupt output for pin state changes with optional masking
* I²C-bus addresses: 8 selectable hardware addresses (pins A0–A2)
* SPI-bus supports standard mode, up to 25 MHz maximum clock frequency
* Operating supply voltage (V_CC): 1.65 V to 5.5 V
* Low quiescent current: 50 μA typical
* High current drive capability: 25 mA sink per pin
* Operating temperature range: –40°C to +85°C
* Package: 24-pin HVQFN or TSSOP options for compact PCB integration
* RoHS-compliant, lead-free, and halogen-free package
* ESD protection: ±4 kV HBM, ±2 kV CDM typical

## Functional Description

The PI4IOE5V9554ZHEX is designed to increase the number of digital I/O pins available to a host controller without additional GPIO ports. The device is organized into two 8-bit ports, each fully programmable as input or output, allowing individual control over each pin. Input pins can be configured to generate interrupts when the logic level changes, facilitating event-driven programming and reducing the need for continuous polling by the host.

I²C-bus mode allows addressing multiple devices on the same bus with configurable hardware addresses, supporting up to eight devices for a total of 128 additional I/O pins. The device also supports SPI-bus mode for fast parallel control and direct register access. Pull-up resistors are internally programmable per pin, eliminating the need for external resistors in many applications.

Each I/O pin is 5 V tolerant, enabling safe interfacing with legacy systems or mixed-voltage designs. The expander also provides configurable polarity inversion, allowing input signals to be logically inverted without software intervention. Output pins can source or sink current up to 25 mA, allowing direct control of LEDs, relays, or other low- to medium-power devices.

## Electrical Characteristics

* Supply voltage (V_CC): 1.65 V to 5.5 V
* Input high voltage (V_IH): 0.7 × V_CC minimum
* Input low voltage (V_IL): 0.3 × V_CC maximum
* Output high voltage (V_OH): V_CC – 0.7 V at I_OH = –4 mA
* Output low voltage (V_OL): 0.4 V maximum at I_OL = 25 mA
* Input leakage current: ±1 μA typical at V_IN = 0 to 5.5 V
* I²C-bus clock frequency: up to 400 kHz (Fast-mode)
* SPI-bus clock frequency: up to 25 MHz maximum
* Standby current: 1 μA typical
* Operating temperature range: –40°C to +85°C
* ESD rating: ±4 kV HBM, ±2 kV CDM
* I/O drive current per pin: 25 mA sink, 4 mA source typical
* Maximum output current per port: 125 mA continuous
* Total device power dissipation: 400 mW typical

## Package and Mechanical Information

* Package types: 24-pin HVQFN (4 mm × 4 mm) or TSSOP-24
* Lead pitch: 0.5 mm for HVQFN, 0.65 mm for TSSOP
* Surface-mount compatible, enabling high-density PCB layouts
* Exposed pad for thermal dissipation in HVQFN package
* RoHS-compliant, lead-free, and halogen-free
* Package optimized for high pin density while maintaining low thermal impedance
* Recommended PCB land pattern ensures low parasitic inductance and effective grounding

## Protection and Reliability Features

* Overvoltage and undervoltage tolerant I/O pins
* Internal ESD protection: ±4 kV HBM, ±2 kV CDM
* Thermal and electrical robustness suitable for industrial and automotive-grade applications
* Configurable output current limits protect connected loads from overcurrent conditions
* Interrupt pin allows fast event notification without continuous CPU polling
* Stable operation over full supply voltage and temperature range
* Low standby current ensures minimal impact on battery-powered applications

## Application Considerations

The PI4IOE5V9554ZHEX is particularly suitable for systems requiring additional digital I/O without redesigning host controllers or microcontroller packages:

* Industrial automation: motor control, sensor interfacing, and status monitoring
* Consumer electronics: LED matrix driving, button inputs, and peripheral control
* Automotive: dashboard control, infotainment systems, and sensor multiplexing
* Network equipment: status signaling and auxiliary I/O expansion
* Low-power and battery-operated devices requiring minimal quiescent current
* I²C/SPI interfacing with FPGAs, microcontrollers, and DSPs for high-performance digital control

When integrating the PI4IOE5V9554ZHEX, designers should ensure proper I²C-bus pull-up resistors, layout consideration to reduce bus capacitance, and careful routing of SPI signals for high-frequency operation. The use of the interrupt output reduces software overhead by allowing event-driven pin monitoring.

## Performance and Efficiency

The device offers high-speed, low-power operation with minimal impact on host CPU resources. I²C-bus operation supports up to 400 kHz, and SPI operation up to 25 MHz, enabling rapid pin state updates. Low standby current (1 μA typical) and programmable output configurations allow efficient power management in battery-powered applications.

The 5 V-tolerant I/Os allow the expander to interface safely with legacy or mixed-voltage devices, reducing the risk of damage. Output drive capability up to 25 mA per pin supports direct control of medium-power loads, reducing the need for additional driver circuits and simplifying system design.

## Compliance and Standards

* RoHS-compliant, lead-free, and halogen-free
* I²C-bus and SPI-bus standard compatible
* Industrial-grade temperature range: –40°C to +85°C
* High-reliability design suitable for automotive and industrial applications
* ESD protected according to JEDEC standards (HBM and CDM)

## Conclusion

The Diodes Inc PI4IOE5V9554ZHEX is a versatile, high-speed, 16-bit I/O expander with dual 8-bit ports, supporting both I²C and SPI interfaces. Its 5 V tolerant inputs and outputs, high drive capability, low-power operation, and integrated interrupt features make it ideal for expanding digital I/O in embedded, industrial, automotive, and consumer systems. With configurable pull-ups, polarity inversion, and robust protection, the device enables reliable and efficient system integration, while its compact surface-mount package supports high-density PCB designs.